Positioning assembly for retaining and positioning a cornea

ABSTRACT

A positioning assembly for retaining, positioning and at least partially exposing a cornea of an eye during a surgical procedure. The positioning assembly includes a positioning segment having a retention plate with an aperture to receive and expose the cornea, and a flange member disposed about the aperture and structured to engage the eye. The positioning assembly further includes a suctioning assembly having a vacuum port extending vertically from the positioning segment and angled outwardly away from a guide track integrally disposed on in the retention plate to define an arcuate cutting path for a microkeratome cutting head assembly. A pivot assembly including at least a post member is further provided which operably interconnects the cutting head assembly and the post member. A cut origination control is provided at the post member to define an origination point.

[0001] This is a continuation application based on a currently pendingU.S. patent application having Ser. No. 09/404,775, filed on Sep. 24,1999, which is a continuation-in-part patent application based on acurrently pending U.S. patent application having Ser. No. 08/840,430,filed on Apr. 29, 1997, which is a continuation of then pending patentapplication filed on Feb. 7, 1996 and having Ser. No. 08/598,180, whichsince issued as U.S. Pat. No. 5,624,456 on Apr. 29, 1997, the contentsof all of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to a medical apparatusused during the performance of eye surgery, and in particular, isdirected towards an improved suction ring, also termed a positioningassembly, for retaining, positioning and exposing a patient's eye forcutting of the cornea during a surgical procedure, such as to correctfor refractive error. More specifically, the present invention isdirected to an easily assembled and safe to use positioning assemblywhich minimizes the potential for improper cutting of the eyelid and/oreye, and further, which is capable of achieving and maintainingeffective attachment on an eye, even one having a latitudinally narrowedocular access, such as may be encountered in certain individuals, mostnotably, but not exclusively, children and persons of Asian descent.

[0004] 2. Description of the Related Art

[0005] The eye works on a principle very similar to that of a camerawherein the iris, or colored portion of the eye about the pupil,functions like a shutter to regulate the amount of light admitted to theinterior of the eye. The cornea or clear window of the eye, and thelens, which is located behind the pupil, serve to focus the light raysfrom an object being viewed onto the retina at the back of the eye. Theretina then transmits the image of the object viewed to the brain viathe optic nerve. Normally, these light rays will be focused exactly onthe retina, which permits the distant object to be seen distinctly andclearly. Deviations from the normal shape of the corneal surfacehowever, produce errors of refraction in the visual process so that theeye becomes unable to focus the image of the distant object on theretina, with the result that one sees a blurred image.

[0006] Many years ago, such refractive errors could only be treated witheyeglasses or contact lens, both of which have well known disadvantagesfor the user. Since then, however, surgical operations have beendeveloped to change the refractive condition of the eye. Several methodsand special instruments have been designed for performing this kind ofsurgery, which are primarily directed to reshape the cornea. It will beappreciated that the goal of corneal reshaping is to modify thecurvature of the cornea, i.e., either to flatten or increase itscurvature depending on the patient's condition, so that light rayspassing through the cornea will thereafter be refracted to focus orconverge directly onto the retina, thereby permitting Gus the patient toview a distant object clearly.

[0007] One such surgical operation is keratomileusis, which requires aprecise reshaping of the cornea by cutting and separating a thin layerof corneal tissue, termed the corneal cap, by lathing that tissue andthen, by suturing the reshaped corneal tissue back into place on theeye. Keratomileusis is viewed, however, as having several drawbacks, andconsequently, has been abandoned in recent years. Automated LamellarKeratectomy (ALK) is another surgical technique which developed as anoutgrowth of keratomileusis. In an ALK procedure, the eye is typicallyfirst numbed by a drop of anesthetic, and then, a device having a ringshaped configuration is placed on the eye to carefully position thecornea (termed “centration” in the art) for being cut by a very finemicrosurgical instrument known as a microkeratome. The microkeratome isgenerally a blade carrying device that must be manually pushed ormechanically driven in a cutting path across the ring shaped device tocut into the cornea. Under an ALK procedure to treat nearsightedness,the microkeratome is typically first used to cut and lift a thin layerof the cornea, instead of severing it, and second, to carry out areshaping of the cornea by way of a second pass of the microkeratomeover the cornea with the cutting element adjusted to pass therethroughat a desired and pre-determined corrective depth. Thereupon the thin,raised layer of corneal tissue is put back in place over the cornea forhealing.

[0008] There have been other significant developments in this field ofart, however. For example, a procedure known as Laser IntrastromalKeratomileusis (LASIK), wherein a laser is utilized to re-shape and/orcontour the cornea, is becoming increasingly accepted as both a safe,painless and rapidly effective procedure for correcting vision problemssuch as, but not limited to, nearsightedness, farsightedness andastigmatism, both regular and irregular. The LASIK procedure iscurrently considered optimal because it allows sculpting of the corneawithout damaging adjacent tissues, and further, because with the aid ofcomputers, the laser can be programmed by a surgeon to more preciselycontrol the amount of tissue removed, and significantly, to permit moreoptions for the reshaping of the cornea. Under LASIK procedures, the eyeis still typically positioned within a ring shaped device and amicrokeratome cutting head assembly is typically also used as apreliminary step to cut and raise a thin layer of corneal tissue inorder to expose underlying portions of the eye for treatment with thelaser. The cutting of a thin layer of corneal tissue is commonly knownas a keratectomy, and in the most common case, a “corneal flap” will becut, which leaves a hinged portion of tissue attached to the cornea,although there are special cases where a “free cap” is cut wherein theraised layer of corneal tissue is left detached from the eye.

[0009] Turning more specifically to how the eye is maintained in thedesired position for a LASIK procedure, the ring shaped device referredto above is commonly used and is attached to the eyeball temporarily byway of a suctioning force or vacuum. As such, such devices are oftenreferred to as suction rings, and a typical suction ring includes anannular, hollow ring that defines a central aperture, which allows thecornea to be exposed therethrough, and an open bottom side having astandard dimension and which is structured to engage the surface of theeye around the cornea. The suction ring is typically in communicationwith a hollow suction tube, which is in fluid flow communication withthe open bottom side of the ring. A vacuum is commonly applied to suchsuction rings, via the suction tube, with a relative vacuum of typicallybetween 20″ Hg and 28″ Hg, being applied, which draws the suction ringdown upon the globe of the eye under the influence of externalatmospheric pressure. As such, the suction ring attaches to the surfaceof the eyeball surrounding the cornea, with the suction force beingapplied and holding the ring in a reasonably secure fashion to theeyeball throughout the LASIK procedure. As a result, the suction ringhas become a conventional device in ophthalmic practice, and it shouldbe noted, is designed to be re-usable so as to accommodate a largenumber of patients over the course of its useful life.

[0010] While the use of such suction rings have become quite common inthe art, there have been some drawbacks associated with them. Forexample, the configuration and size of known suction rings do notreadily permit them to be comfortably and/or properly positioned withinthe ocular recess of many persons. More specifically, it has beendetermined that some individuals, and especially children and persons ofAsian decent, tend to exhibit certain physical characteristics whichresult in there being a somewhat constricted area available forplacement of the suction ring. For example, such individuals may eitherhave a more narrow ocular recess and/or may not be able to open theireyes as wide as some other persons, especially in the latitudinal and/orup and down direction. This restricted access can often lead todifficulties for the practitioner performing a surgical procedure suchas LASIK on the eye, as an insufficient surface area for propersecurement of a traditional suction ring exists.

[0011] As a result, it would be highly beneficial to provide amicrokeratome assembly, and in particular an improved suction ring foruse with such an assembly, which is especially well suited for use inthe eyes of all patients, including those having latitudinally smallerocular accesses. Any such improved suction ring developed, however,should be able to be effectively and comfortably secured to the exposedportions of the patient's eye, while still exposing and presenting asufficient depth and/or diameter of the cornea for cutting by themicrokeratome cutting head assembly. Furthermore, if any such improvedsuction ring were developed, it would be very it beneficial if it werestructured for effective use with a cutting head assembly of the typeconfigured to cut along an arcuate path, such as that disclosed in U.S.Pat. No. 5,624,456 and considered by many to perform a keratectomy withoptimal results, without interfering with the cutting process and/ordiminishing its accuracy, despite there being a more confined area orocular recess.

[0012] It is also noted that conventional suction rings can be difficultto manufacture and/or assemble, particularly given the degree ofprecision which is necessary for safe and effective use duringopthamological procedures. If a suction ring were developed which issuitable for a smaller ocular recess, which commonly found on childrenand persons of Asian descent, these issues would also have to beaddressed satisfactorily. Thus, it would be beneficial to provide animproved suction ring or positioning assembly which integrates all ofthe necessary components into an efficient, streamlined, and compactconfiguration, which is readily capable of being manufactured accuratelyand precisely, and which still allows for the safe and preciseutilization of a microkeratome assembly. Lastly, it would also bebeneficial if any improved suction ring were developed which couldreasonably ensure that during a keratectomy, the microkeratome cuttinghead assembly will initiate cutting of the cornea at a uniform andrather precise position relative to the eyelid and/or cornea so as toavoid the possibility that an improper cut will occur. More inparticular, it would be beneficial to provide an improved suction ringor positioning assembly that does not allow the cutting of an incisionto begin unless the cutting head assembly is properly positioned.

SUMMARY OF THE INVENTION

[0013] The present invention is structured to address these and otherneeds which remain in the art and is directed towards an improvedsuction ring, and more specifically, a positioning assembly forretaining and positioning the cornea of patient's eye for theperformance of a surgical procedure thereon. The positioning assembly ofthe present invention is, in at least one embodiment, especially suitedfor use on patients exhibiting a latitudinally narrowed ocular recess orocular access, meaning that dimension which corresponds to the directionof blinking, as is commonly found on children and individuals of Asiandescent. Also, while the present invention has application to the eye ofany patient, it is expected that it will typically be used on the humaneye.

[0014] More in particular, the present invention is directed towards apositioning assembly which at least partially exposes, positions andretains an eye during a surgical procedure. The positioning assembly is,therefore, preferably incorporated as part of a microkeratome assembly,and as a result, may be utilized in conjunction with a microkeratomecutting head assembly that is configured to form an incision in and/orcut across the eye, whether that results in the creation of a cornealflap or not. The positioning assembly includes a positioning segmentwhich is structured to retain and position the eye during the surgicalprocedure such that the cornea is maintained in a properly exposedposition throughout. As such, the positioning segment includes aretention plate. The retention plate preferably includes a generallyplanar configuration, and has an aperture defined therein. The aperture,which in the preferred embodiment is generally centrally disposed on orwithin the retention plate, is structured to receive and expose thecornea of the eye therein, so as to generally define the area to be cut.

[0015] The position segment also includes a flange member. The flangemember depends generally downward from the retention plate and isdisposed in preferably enclosing relation about the aperture. As such,the flange member is structured to engage the eye at least substantiallyalong a bottom edge thereof. Accordingly, a vacuum chamber is generallydefined between the aperture, bottom edge of the flange member, and thesurface of the eye extending therebetween. The flange member of thepresent invention is also preferably disposed a relatively close, spacedapart distance from the aperture of the positioning segment, at leastgenerally along a latitudinal radius thereof. As a result, incircumstances wherein the patient has a latitudinally narrowed ocularaccess, not as much of the surface of the eye need be exposed by theocular access in order to achieve effective contact between thepositioning segment and the eye, and in order to effectively expose asufficient quantity of the cornea within the aperture.

[0016] The positioning assembly of the present invention may furtherinclude, at least in part, a suctioning assembly. In particular, asuctioning assembly is preferably operatively associated with thepositioning segment, preferably at the vacuum chamber, thereby at leasttemporarily attaching the positioning segment to the eye. Specifically,the suctioning assembly includes a vacuum port connected in fluid flowcommunication between the vacuum chamber and an exterior source ofvacuum. As a result, a suction force is applied at the vacuum chamber,and effective securement of the positioning assembly to the eye isachieved. Preferably, however, the vacuum port, unlike traditional,perpendicularly-oriented vacuum ports, is at least partially angledoutwardly away from the vertical axis of the aperture, thereby providingeffective clearance for movement of the microkeratome cutting headassembly, as will be described subsequently herein.

[0017] In the more preferred embodiments of the present invention, thepositioning assembly of the present invention includes a guide track.The guide track is preferably integrally formed by with the positioningsegment, and further, defines a preferably arcuate cutting path, whichguides the microkeratome cutting head assembly at least partially acrossthe aperture defined in the retention plate. The guide track preferablyextends latitudinally beyond the retention plate of the positioningsegment and is preferably disposed in close proximity to the vacuumport. As such, the generally outward, angled nature of the vacuum portaway from the guide track ensures that a suction tube or like structurecoupled to the vacuum port will not interfere with the movement of thecutting head assembly in operative association with the guide track.

[0018] Additionally, the positioning assembly preferably includes apivot assembly and associated coupling member. Specifically, the pivotassembly defines a pivot axis for the cutting head assembly, which asindicated preferably moves arcuately across the aperture as defined atleast by the guide track and also preferably by the pivot assembly.Preferably, a post member is included in the pivot assembly to definethe pivot axis about which the cutting head assembly rotates, thecoupling member pivotally interconnecting the post member with thecutting head assembly at least for this purpose. The pivot assembly,however, also further comprises a cut origination control. The cutorigination control is structured to define at least one originationpoint for the commencement of operative pivotal movement of the couplingmember, and accordingly the cutting head assembly, across thepositioning segment. As a result, a practitioner is ensured that thecutting head assembly engages the eye and begins the formation of theincision only at a proper point, such as at the edge of the aperture,and generally cannot be inadvertently positioned to form an incisioncommencing at an intermediary point of the exposed cornea.

[0019] These and other features of the present invention are describedin further detail in the following detailed description and associateddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a fuller understanding of the nature of the presentinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawings in which:

[0021]FIG. 1 is a perspective view of the positioning assembly of thepresent invention;

[0022]FIG. 2 is a cross section view of the positioning assembly of thepresent invention;

[0023]FIG. 3 is an exploded perspective view of the coupling assembly ofthe positioning assembly, and an associated microkeratome cutting headassembly;

[0024]FIG. 4 is an isolated side view of the post member of the pivotassembly of the present invention;

[0025]FIG. 5 is a top plan view of the post member;

[0026]FIG. 6 is a cross-section of the coupling assembly;

[0027]FIG. 7 is a top plan view of the positioning assembly of thepresent invention without the post member and coupling assembly coupledthereto;

[0028]FIG. 8 is an illustration of a microkeratome assemblyincorporating the positioning assembly of the present inventionappropriately disposed on a corresponding eyes of a patient; and

[0029] FIGS. 9A-9C are a series of sequential illustrationsdemonstrating a normal cutting path for a microkeratome assembly withwhich the positioning assembly of the present invention is preferablyassociated.

[0030] Like reference numerals refer to like parts throughout theseveral views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031] Illustrated throughout the drawings, the present invention isdirected generally towards a positioning assembly for improved retainingand positioning of a patient's eye, and preferably the cornea of thepatient's eye which is to be cut during a surgical operation, and isgenerally indicated by reference numeral 10. More specifically, thepresent invention is directed towards a more compact, precisionassemblable and manufacturable, safety enhancing and stable positioningassembly 10 that can be used not only on the average patient, but whichMS can also be used effectively on a patient having a latitudinallyreduced ocular access wherein the eye is contained. In particular, theocular access is generally defined as the eye socket and associated eyelid, all of which limit and/or otherwise restrict the amount of apatient's eyeball that can be exposed, such as for securing to apositioning assembly. In some cases, and most prevalently with childrenand patient's having characteristic, Asian facial features, the ocularaccess exhibits a smaller than normal latitudinal dimension. (Forpurposes of this description, a latitudinal dimension is defined as anup and down dimension relative to the patient's face, up being towardsthe patient's eyebrow and down being towards the patient's chin.) As aresult, a conventional positioning assembly is generally not able tosufficiently engage the latitudinal sides of the eyeball. Naturally,such a restriction results in improper centration, and/or less of thecornea being exposed for cutting. As will be described, the presentinvention provides a more compact configuration, which is beneficial notonly in the case of a latitudinally reduced ocular access, but which isgenerally beneficial when performing surgery on the eye for a variety ofreasons including ease and precision of assembly, safety, and stabilityduring cutting.

[0032] The positioning assembly 10 of the present invention ispreferably directed for use with a microkeratome assembly such as, butnot necessarily like the one described in U.S. Pat. No. 5,642,456, andincorporated herein by reference. As illustrated in FIGS. 1, 2 and 7,the positioning assembly 10 comprises a positioning segment 20, alsoknown as an eye positioning ring. The positioning segment 20 preferablyincludes an enclosed ring configuration, so as to maximize itsengagement with the eye, and is used to centrate the eye, that is, toretain, position and properly present the cornea of a patient's eyeballin a precise and aligned manner for surgery. Thus, the positioningsegment 20 has a main body which includes and defines a preferablyenclosed aperture 25 therein. The aperture 25 is sized to receive andpermit the cornea C, of the eye to pass therethrough so as to expose thecornea C, and a pre-determined depth thereof, for cutting duringsurgery. Typically, the cornea C will be cut during surgery when amicrokeratome cutting head assembly 15, also preferably part of themicrokeratome assembly, is moved over the face of the positioningsegment 20 and thus, over the exposed cornea C, which as is clear fromthe drawings, protrudes through the aperture 25. The aperture 25 itselfis preferably sized to expose a sufficient amount of the cornea so thata diameter of generally about 7.5 to 10 millimeters may be cut. Thepositioning segment 20 is preferably formed of a rigid material andpreferably, a metallic material. Ideally, however, the positioningsegment 20 will be made of a high grade stainless steel, which enhancesprecision engagement with the eyeball, can go be formed to have asmooth, safe and glare-retardant surface finish, and which provides forease of sterilization. Along thee lines, although the presentpositioning assembly may be made disposable, out of a variety ofmaterials, and/or molded of plastic or metal, in the illustratedembodiment, the positioning assembly 10 is preferably machined so as toachieve the degree of precision and quality generally desired.

[0033] As illustrated in the figures, the main body of the positioningsegment 20 is preferably defined by a generally circular shape about theaperture 25, although it will be appreciated that it could be formed tohave another shape, such as a square, rectangular, hexagonal or othershape about the aperture 25, and still function for the intendedpurpose. Moreover, the entire positioning assembly 10 is preferablyconfigured in a generally tear drop type shape. In the preferredembodiment, the main body of the positioning segment 20 comprises aretention plate 23, which includes the aperture 25 defined therein, andpreferably a flange member 24 extending generally downwardly from theretention plate 23 and defining a generally open bottom side to the mainbody 22. Ideally, the flange member 24 is disposed in spaced apart,generally surrounding relation to the aperture 25 defined in theretention plate 23. Also in the preferred embodiment, the flange member24 of the positioning segment 20 preferably includes a lower edge 27which is structured and disposed to engage the portion of the eye aboutthe cornea in a fluid impervious manner. Similarly, the retention plate23 may also be said to include an interior rim 26 disposed insurrounding, defining relation about the aperture 25, and which isstructured to engage the eye disposed therein, also in a fluidimpervious manner. It will therefore be appreciated that upon thepositioning segment 20 being disposed in engaging relation with the eye,that an effective, generally air-tight seal can be achieved about theeyeball and a vacuum chamber 22 between retention plate 23 and flangemember 24. Additionally, as illustrated in FIG. 2, a channel 29 may alsobe defined in the vacuum chamber 22, the channel 29 enhancing theeffectiveness of a vacuum applied, either alone or in combination with arigid or flexible insert as provided in U.S. Pat. No. 5,772,675.

[0034] Looking further to the flange member 24, as it defines the outerperimeter for engagement with the eye, in the illustrated embodiment,the flange member 24 is disposed in more closely spaced relation to aperimeter of the aperture 25 than is the case in conventionalpositioning assemblies. Although this closer spacing may be defined onlyat a latitudinal radius of the aperture 25 in response to the reduceddimension of the narrowed ocular access, it is generally preferred thatthe flange member 24 define a circular configuration which is uniformlyspaced from the aperture 25 and facilitates proper centration of theeye. In the illustrated embodiment, the latitudinal diameter of theflange member 24, generally at the lower edge 27 which engages the eye,is generally between about 0.675 and 0.725 inches. More precisely, alatitudinal diameter of less than generally about 0.79 inches, or 0.708inches (18 mm) is preferred to correspond an aperture 25 diameter ofgenerally between about 0.350 to 0.475 inches, or more precisely, 0.420inches in order to form an 8.5 mm flap. For example, the presentinvention, with the closely space flange member 24 can be utilized toform a 7.5 mm, 8.5 mm, 9.5 mm, or other dimension incision merely bymodifying a size of the aperture to the corresponding 0.375 inch, 0.420inch and 0.465 inch diameters. As can be appreciated, however, reducinga diameter of the flange member 24, while retaining a necessary sizedopening, reduces the depth to which the positioning assembly 10 can passdown onto the eye. Still, however, it is desirable to maintain the samediameter of the eye exposed through the cornea, and through preferably astandard dimension aperture 25 so as to generate the appropriately sizedcorneal flap. As such, the present invention also preferably includes areduced depth of the positioning segment 20, as defined by the flangemember 24. In the illustrated embodiment, the depth of the positioningsegment 20, as generally defined from an upper surface of the retentionplate 23 to the lower edge 27 of the flange member 24, is preferablyless than generally about 0.175 inches and more preferably between about0.1 to 0.15 inches. In the illustrated embodiment wherein a preferred0.420 inch diameter aperture 25 and 0.708 diameter flange member areutilized, the preferred depth is 0.115 inches. As a result of thepreceding, however, a sufficient portion of the eye is exposed throughthe aperture 25, and restrictions in access to the eye based upon thephysical characteristics of the patient are obviated, with thepositioning segment 20 fully and securely engaging the surface of theeye.

[0035] The positioning assembly of the present invention is furtherdirected for use with and may at least partially comprise a suctioningassembly 30 for at least temporarily attaching the positioning segment20 to the eye on which surgery is to be performed once it has beenproperly positioned thereon. Preferably, the suctioning assembly 30comprises a vacuum port 32 formed in the positioning segment 20 and avacuum assembly (not shown) for providing a suction force. The vacuumassembly is structured to apply a suction force which is sufficient toattach the positioning segment 20 to the eyeball about the cornea, C,and cause the cornea to be urged upwardly and to protrude through theaperture 25 of the positioning segment 20, while not being so strong asto cause damage to the eyeball. It will be appreciated from the drawingsthat the vacuum port 32 formed in the positioning segment 20 is operablycoupled to and in fluid flow communication with the vacuum assembly suchthat the suction force is applied therethrough. Specifically, apreferably removable, externally threaded vacuum handle (not shown),which may also provide a convenient means of grasping and manipulatingthe positioning assembly 10, is preferably screwed into the vacuum port32 in a secure, fluid impervious manner. Indeed, such an internallythreaded configuration of at least a portion of the vacuum port 32ensures a more secure engagement and significantly facilitates cleaningof the positioning assembly 10 as the vacuum handle can be secured toensure no gap, which could potentially become clogged, is presenttherebetween, and easy access to the interior of the vacuum port 32 canbe achieved for cleaning. Moreover, in the preferred embodiment, thevacuum port 32 extends to an undersurface 28 of positioning segment 20either through retention plate 23 or flange member 24 and into thevacuum chamber 22. Thus, the vacuum port 32 is disposed to provide asuction force, once the vacuum assembly is activated, to a pointradially exterior of the aperture 25 and radially interior of the flangemember 24, so as to form a seal about the cornea of the eye about toundergo surgery. It should be clear at this point that the structure ofpositioning segment 20, when accompanied by a suction force, acts toproperly position and align the cornea C, for surgery and to generallymaintain that position during surgery. Typically, a vacuum of about 25inches of Hg at sea level will be used.

[0036] The positioning assembly 10 of the present invention alsopreferably includes a guide track 40 formed thereon. The guide track 40is preferably formed directly on and integrally with the positioningsegment 20 so as to guide and facilitate movement of the microkeratomecutting head assembly 15 during the surgical cutting of the cornea. Theintegral machining is preferred in the illustrated, more compactembodiment, as it ensures that a secure and stable connection betweenthe guide track 40 and the positioning segment 20 is maintained at alltimes, and ensures that no mis-alignment therebetween will occur as aresult of assembly and manufacturing. In particular, some positioningassemblies include a separately machined guide track secured to thepositioning segment 20 by one, but typically two or more screws. Two ormore screws were generally preferred because the use of one screw mightlead to improper alignment of the guide track relative to the apertureif extreme care and precision is not maintained during manufacture andassembly. Based upon the more compact design of the illustratedembodiment, however, it is generally impractical to include multiplescrews. Accordingly, in the illustrated more compact embodiment, as wellas in other embodiments, in order to maintain precision and ease ofassembly, the guide track 40 is preferably integrally formed, such as bymachining to a width of about 0.03 inches, with the positioning segment.Also, referring to FIGS. 1 and 2, in the preferred embodiment, the guidetrack 40 extends along a length of at least one side of positioningsegment 20, but preferably extends latitudinally beyond the positioningsegment 20 so that engagement between the cutting head assembly and theguide track occurs at a point before the aperture. The present inventionrecognizes that although a limited dimension must be employed for theoutermost engagement by the flange member 24 with the eye, a relativelyelevated guide track 40 need not be constrained to the same extent. Theguide track 40 of the present invention is configured to extend beyondthe retention plate 23 so as to further guide and/or stabilize themicrokeratome cutting head assembly 15 before and during a cut acrossthe aperture 25, thereby ensuring complete formation of the corneal flapdesired in most cases, and at a starting point before the edge of theaperture 25. It will also be appreciated from the drawings that theguide track 40 includes a toothed upper surface 42 and a retaining lip44, and extends across the positioning segment in a generally arcuate orsemi-circular path. The guide track thereby retains and/or pins thecutting head assembly 15 operatively and downwardly engaged on the eye,and may at least partially guide the movement of the cutting headassembly 15, along the arcuate cutting path best illustrated in FIGS.9A-9C with regard to a left eye, such as through the engagement of agear structure of the cutting head assembly 15 on the toothed uppersurface 42 of the guide track 400.

[0037] Looking once again to the vacuum port 32 of the suctioningassembly 30, as illustrated in the Figures, it is preferably angledoutwardly away from a vertical axis of the aperture 25 and/or outwardlyaway from the guide track 40. As a result, when a hose or other conduitis coupled thereto for supplying the suction force, neither the vacuumport or the conduit will obstruct or otherwise interfere with themovement of the cutting head assembly 15 at least partially over theguide track 40. Furthermore, in the illustrated embodiment, such aconfiguration permits the more compact, preferably circularconfiguration of the positioning segment 20 to be maintained, whilestill effectively directing the suction force to the vacuum chamber 22.Moreover, the integral formation of the guide track 40 with thepositioning segment, and generally the vacuum port 32, furthercontributes to the more compact configuration, as a space for screwsand/or other fasteners need not be provided. It is also noted that thevacuum port 32 itself preferably does not extend above a plane of theguide track 40, also contributing to the streamlined nature of thepresent positioning assembly 10.

[0038] Also in the illustrated embodiment, the present invention alsopreferably includes a pivot assembly. The pivot assembly is structuredto provide increased stability to the cutting head assembly 15 duringits movement along the arcuate path, and also preferably to define apivot axis which can stabilize or alternately further guide the movementof the cutting head assembly 15 in conjunction with the guide track 40.The pivot assembly preferably includes a post member 50. The post member50 is preferably a rigid upstanding element disposed generally oppositethe guide track 40. As will again be appreciated from the drawings, inthe preferred embodiment, wherein positioning assembly 10 has atear-drop shape, a base section 55, also preferably part of the pivotassembly, is integrally formed with and extends from the positioningsegment 20. The base section 55 provides a support surface at which thepreferably separately formed post member is secured, as will bedescribed subsequently, during assembly. Moreover, from the explanationwhich follows, it will become clear that guide track 40 and post member50 permit the cutting head assembly 15 of the invention, in a preferredembodiment, to become effectively guided and securely received on thepositioning assembly 10 in two places, while still permitting thecutting head assembly 15 to be smoothly and slidably moved over thepositioning segment 20 along a generally arcuate path, by way of apivoting motion about the pivot axis defined by the post member 50. Ofcourse, the positioning assembly 10 could also be formed to includeanother guide track, which extends along a length of the other side ofpositioning segment 20, also preferably, on an upper surface thereof, soas to also permit the cutting head assembly 15 of the invention tobecome effectively guided and securely received on the positioningsegment 20 in two places while still permitting the cutting headassembly 15 to be smoothly and slidable moved over positioning segment20 along a generally arcuate path. As a result, either the pivotassembly and/or one or more guide tracks function to direct the arcuatemovement of the cutting head assembly 15.

[0039] Also preferably included as part of the pivot assembly is MIX acoupling member 70. While the cutting head assembly 15 might be directlyand yet movably engaged with the positioning segment 20 for performingan operation on the eye, preferably, the coupling member 70 is utilizedas part of the invention, which is structured and disposed to movablyand operably couple the cutting head assembly 15 to the positioningsegment 20, preferably via the post member 50, while simultaneouslypermitting movement of the cutting head assembly 15 relative topositioning segment 20. As illustrated in FIG. 3, the coupling member 70preferably comprises two segments: a) a retaining segment 72 and b) apivot segment 74. The retaining segment 72 is preferably structured anddisposed to be fitted onto a top surface of the cutting head assembly 15so as to be effectively and removably secured thereto, and move inassociation with the movement of the cutting head assembly 15. Turningto the pivot segment 74 of coupling member 70, it is structured anddisposed to be coupled to the post member 50 and to permit couplingmember 70, and accordingly, the cutting head assembly 15 connectedthereto, to pivotally move about the pivot axis. Preferably, the pivotsegment 74 includes a bushing having a bore 75 formed therein, which issized to receive a substantial height of the post member 50, therebycaptivating it therein.

[0040] Looking once again to the pivot assembly, and preferably the postmember 50 thereof, it preferably defines a cut origination control. Thecut origination control is structured to define at least one originationpoint, as in FIG. 9A, at which operative pivotal movement of thecoupling member 70, and accordingly the cutting head assembly 15, aboutthe pivot axis commences. In particular, the cut origination control isconfigured to substantially ensure that the cutting head assembly 15cannot engage the eye and/or the guide track 40, such that an incisioncan be formed, unless it is properly disposed an appropriate originationpoint. Additionally, the cut origination control ensures that thecutting head assembly 15 is not positioned so as to begin to cut theretention plate 23, eye lid and/or other instruments and articlesdisposed peripherally to the aperture 25 and the eye. In the illustratedembodiment, the cut origination control includes at least one, butpreferably a pair of slots 51, 52 defined in the post member 50. Theslots 51, 52, which are preferably, but not necessarily, generallyvertically oriented, each define an origination point, such as for theleft and right eye, and in the illustrated embodiment are disposed at anangular separation of approximately 100 degrees from center line tocenter line. In particular, as the positioning assembly 10 of thepresent invention is structured preferably for use on either eye, asillustrated in FIG. 8, a different origination point on opposite sidesof the positioning segment 20 must be defined depending upon thedirection of travel. In either instance, however, the slot 51, 52 isstructured to at least partially receive a restrictor element 78 definedpreferably in the bore 75 of the coupling member 70. Specifically, therestrictor element is structured and disposed to fit within acorresponding slot 51, 52, but to restrict passage of the couplingmember 70 onto the post member 50 if they are not properly aligned.Along these lines, it is noted that multiple and/or more elaborateconfigurations could be equivalently utilized so as to provide therestriction if the members are not aligned. Furthermore, althoughinadvertent passage of the restrictor element 78 into the incorrect slot51, 52 could result, the necessary positioning of said slots 51, 52 issuch that the cutting head assembly 15 would be disposed with its bladebeyond the aperture 25 such that an improper cut could still not result.

[0041] Because the orientation of the slots 51, 52 relative to thepositioning segment 20 generally defines the location of the originationpoint, it is necessary to ensure that the post member 50 be secured tothe base section 55 in a precisely aligned manner. Although a multiplescrew configuration could be utilized to provide a certain degree ofprecision alignment, in the illustrated embodiment, the post member 50includes an alignment segment 57 structured to operatively engage thebase section 55 so as to ensure properly axially aligned securement ofthe post member 50 thereto. In particular, the base section 55 includesan alignment edge 56 which is matingly engaged by the alignment segment57 of the post member 50. In the illustrated embodiment, the alignmentsegment 57 and alignment edge 56 are straight surfaces which can beconfrontingly engaged to provide the aligned securement, however, othermating configurations could also be employed. Based upon the precedingstructure, however, proper, precise aligned securement of the postmember 50 on the base section 55 can be achieved, such as through thepassage of a fastener element through an opening 55′ in the base section55 and to the post member 50.

[0042] As a result, based upon the preceding, the cutting head assembly15 cannot engage the eye unless it is at the appropriate starting point.Furthermore, however, so as to permit the requisite pivotal movementbetween the post member 50 and the coupling member 70, a channel 58 ispreferably formed in the post member 50 so as to permit slided passageof the restrictor element 78 therethrough during pivotal movement of thecoupling member 70, and accordingly the cutting head assembly 15relative to the post member 50. It is of course understood that therestrictor member could be equivalently disposed on the post member,with the slot(s) defined in the coupling member. In eitherconfiguration, however, the channel 58 also functions to ensure that thecoupling member 70 does not pivot relative to the post member 50, butrather that it is pinned down into a uniform plane of motion in much thesame manner that the retaining lip 44 pins down the cutting headassembly 15 at the guide track 40.

[0043] Since many modifications, variations and changes in detail can bemade to the described preferred embodiment of the invention, it isintended that all matters in the foregoing description and shown in theaccompanying drawings be interpreted in the illustrative and not in alimiting sense. Thus, the scope of the invention should be determined bythe appended claims and their legal equivalents.

[0044] Now that the invention has been described,

What is claimed is:
 1. For retaining, positioning and at least partiallyexposing during a surgical procedure, a cornea of an eye that isdisposed in a latitudinally narrowed ocular access, a positioningassembly comprising: a) a positioning segment, said positioning segmentincluding a retention plate; b) said retention plate including anaperture defined therein and structured to receive and expose the corneaof the eye therein; c) said positioning segment further including aflange member disposed about said aperture and structured to engage theeye; and d) said flange member being disposed a closely spaced apartdistance from said aperture at least at a latitudinal radius thereof. 2.A positioning assembly as recited in claim 1 further comprising a pivotassembly structured to define a pivot axis for a cutting head assembly'smovement across the aperture.
 3. A positioning assembly as recited inclaim 2 wherein said pivot assembly comprises at least a post member togenerally define said pivot axis.
 4. A positioning assembly as recitedin claim 3 further comprising a coupling member, said coupling memberpivotally interconnecting said pivot assembly and said cutting headassembly.
 5. A positioning assembly as recited in claim 4 wherein saidpivot assembly further comprises a cut origination control structured todefine an origination point for operative pivotal movement of saidcoupling member, and accordingly the cutting head assembly.
 6. Apositioning assembly as recited in claim 5 wherein said cut originationcontrol comprises a slot defined in said post member, and said couplingmember includes a restrictor element structured to restrict operativeengagement of said coupling member with said post member unlesscorrespondingly disposed in said slot.
 7. For retaining, positioning andat least partially exposing a cornea of an eye during a surgicalprocedure, a positioning assembly comprising: a) a positioning segment,said positioning segment including a retention plate; b) said retentionplate including an aperture defined therein and structured to receiveand expose the cornea of the eye therein; c) a suctioning assemblyoperably associated with said positioning segment for at leasttemporarily attaching said positioning segment to the eye; and d) saidsuctioning assembly including a vacuum port, said vacuum port being atleast partially outwardly angled away from a vertical axis of saidaperture.
 8. A positioning assembly as recited in claim 7 furthercomprising a guide track, at least said guide track structured to guidea cutting head assembly at least partially across said aperture.
 9. Apositioning assembly as recited in claim 8 wherein said vacuum port isat least partially integrally formed with said guide track.
 10. Apositioning assembly as recited in claim 8 wherein said vacuum port isat least partially angled away from said guide track so as to minimizeinterference with movement of said cutting head assembly.
 11. Apositioning assembly as recited in claim 10 wherein said guide trackdefines a generally arcuate path.
 12. For retaining, positioning and atleast partially exposing a cornea of an eye during a surgical procedure,a positioning assembly comprising: a) a positioning segment, saidpositioning segment including a retention plate; b) said retention plateincluding an aperture defined therein and structured to receive andexpose the cornea of the eye therein; c) a guide track, at least saidguide track structured to guide a cutting head assembly at leastpartially across said aperture; and d) said guide track being integrallyformed with said positioning segment.
 13. A positioning assembly asrecited in claim 12 wherein said guide track defines a generally arcuatepath.
 14. A positioning assembly as recited in claim 12 wherein saidguide track extends latitudinally beyond said retention plate of saidpositioning segment.
 15. A positioning assembly as recited in claim 12further at least partially including a suctioning assembly operablyassociated with said positioning segment for at least temporarilyattaching said positioning segment to the eye, said suctioning assemblyincluding a vacuum port.
 16. A positioning assembly as recited in claim15 wherein said vacuum port is at least partially integrally formed withsaid guide track.
 17. A positioning assembly as recited in claim 15wherein said vacuum port is at least partially outwardly angled awayfrom said guide track so as to minimize interference with movement ofsaid cutting head assembly.
 18. For retaining, positioning and at leastpartially exposing a cornea of an eye during a surgical procedure, apositioning assembly comprising: a) a positioning segment, saidpositioning segment including a retention plate; b) said retention plateincluding an aperture defined therein and structured to receive andexpose the cornea of the eye therein; c) a pivot assembly structured todefine a pivot axis for a cutting head assembly which moves arcuatelyacross the aperture; d) said pivot assembly including at least a postmember to generally define said pivot axis; e) a coupling member, saidcoupling member pivotally interconnecting said post member and saidcutting head assembly; and f) said pivot assembly further comprising acut origination control structured to define an origination point foroperative pivotal movement of said coupling member, and accordingly thecutting head assembly.
 19. A positioning assembly as recited in claim 18wherein said cut origination control comprises a slot defined in saidpost member, and said coupling member includes a restrictor elementstructured to restrict operative engagement of said coupling member withsaid post member unless correspondingly disposed in said slot.
 20. Forretaining, positioning and at least partially exposing a cornea of aneye during a surgical procedure, a positioning assembly comprising: a) apositioning segment, said positioning segment including a retentionplate; b) said retention plate including an aperture defined therein andstructured to receive and expose the cornea of the eye therein; c) apost member structured to at least partially define a pivot axis for acutting head assembly which moves arcuately across said aperture; d) abase section, said post member operatively extending from said basesection; and e) said post member including an alignment segmentstructured to operatively engage said base section so as to ensureproperly axially aligned securement of said post member thereto.
 21. Apositioning assembly as recited in claim 20 wherein said base sectionincludes an alignment edge, said alignment segment of said post memberstructured to matingly engage said alignment edge.
 22. For retaining,positioning and at least partially exposing during a surgical procedure,a cornea of an eye that is disposed in a latitudinally narrowed ocularaccess, a positioning assembly comprising: a) a positioning segment,said positioning segment including a retention plate; b) said retentionplate including an aperture defined therein and structured to receiveand expose the cornea of the eye therein; c) said positioning segmentfurther including a flange member disposed about said aperture andstructured to engage the eye disposed therein; and d) said flange memberincluding a latitudinal diameter of generally between about 0.675 and0.725 inches.